TBILISI, Georgia - Pope Francis' efforts to improve relations with the Georgian Orthodox Church suffered a setback Saturday after the patriarchate decided at the last minute not to send an official delegation to his Mass and reminded the Orthodox faithful they cannot participate in Catholic services.

Francis still pressed on with his agenda, insisting that Catholics must never try to convert Orthodox and bowing in prayer alongside the Orthodox patriarch after they both lit a candle in the Orthodox cathedral.

Francis called for the historical divisions that have "lacerated" Christianity to be healed through patience, trust and dialogue.

"We are called to be one in Jesus Christ and to avoid putting disharmony and divisions between the baptized first, because what unites us is much more than what divides us," he told Patriarch Ilia, amid the Aramaic chants and hypnotic bells tolling at the cathedral in the spiritual capital of the Georgian Orthodox Church.

Saturday's developments on the second and final day of Francis' visit to Georgia reflected the "one step forward, two steps back" progress that often accompanies the Vatican's outreach to the Orthodox Church, which split from the Catholic Church over 1,000 years ago over issues including the primacy of the pope.

On Sunday, Francis heads to largely Shiite Muslim Azerbaijan, where the Catholic Church enjoys good relations with the government despite allegations of human rights abuses and the suppression of dissent.

Before Francis' Caucasus visit, the Vatican spokesman had said the Georgian Orthodox Patriarchate would send a delegation to the Mass in a Tbilisi sports stadium "in a sign of the rapport" — suggesting that the chill which had clouded St. John Paul II's visit in 1999 had warmed. And Francis had received an unexpectedly warm welcome from the Orthodox leader upon his arrival Friday.

But Orthodox patriarchate spokeswoman Nato Asatiani said Saturday that the delegation had stayed away from the Mass "by mutual agreement." The patriarchate updated a statement on its website saying "as long as there are dogmatic differences between our churches, Orthodox believers will not participate in their prayers."

The decision apparently came after Francis' arrival in Tbilisi was met with protests by hard-line Orthodox opposed to ecumenical initiatives. On Saturday, about 100 members of the hard-line Union of Orthodox Parents demonstrated outside the stadium where Francis celebrated Mass. Other protesters greeted him at the Orthodox cathedral and outside a Catholic-run rehab centre.

"It's typical proselytizing," said protester Father David Klividze. "Can you imagine how it would be if a Sunni preacher came to Shiite Iran and conducted prayers in a stadium or somewhere else? Such a thing could not be."

Georgia is overwhelmingly Orthodox, with less than 3 per cent of its population — or about 112,000 people — Catholic, according to Vatican statistics.

Vatican spokesman Greg Burke said the Vatican accepted the Orthodox decision not to attend the Mass.

An Orthodox delegation at the Mass would have been an exception to the rule, and Francis had been scheduled to personally greet the delegation. In their absence, Francis instead thanked "those Orthodox faithful" who were present, including members of an Orthodox choir.

Organizers had expected the Meskhi sports stadium, capacity 27,000, to be full for the Mass, but it held a few thousand people when Francis began the celebration. There was no official explanation for the low turnout of Catholics.

Other than Georgian President Giorgi Margvelashvili, there were no prominent Georgian politicians at the Mass. With a parliamentary election next week, politicians might have been reluctant to alienate hard-line Orthodox voters.

Francis insisted that Catholics must never seek to convert Orthodox, saying they are Catholics' brothers and sisters, children of the same God.

"Proselytism is a grave sin against ecumenism," Francis told Catholic priests and seminarians after his Mass.

Prime Minister Giorgi Kvirikashvili and other cabinet ministers did show up for Francis' visit to the seat of the Orthodox church, where he pressed his call for improved Catholic-Orthodox ties.

The Orthodox cathedral is located in Mtskheta, the spiritual capital of Georgia and where Christianity took root in the 4th century. The 11th-century frescoed Svetitskhoveli cathedral, one of three Mtskheta monuments on the UNESCO World Heritage list, is said to have housed Christ's tunic.

Francis referred to the precious relic Saturday.

"The holy tunic, a mystery of unity, exhorts us to feel deep pain over the historical divisions which have arisen among Christians. These are the true and real lacerations that wound the Lord's flesh," he said. Christian hope, he added, "gives us the incentive to believe that differences can be healed and obstacles removed. It invites us never to miss opportunities for encounter and dialogue."

Ilia welcomed Francis warmly to his church, expressing his "profound esteem and brotherly love" and embracing him with three kisses on the cheek.

"May God's will unify Christians on the foundation of the true faith," he said.

While hard-liners opposed the pope's visit, other Orthodox welcomed it.

"The visit of the pope is very significant," said Amiran Tsiklauri, a resident of Tbilisi. "The pope is not only spiritual leader for Catholics but also the person who calls and urges for peace around the world."